Vibrating apparatus



June 20, 1950 G. H. STRAIN VIBRATING APPARATUS 2 Sheets-Sheet 1 Filed Oct. I5, 1944 G. H. STRAIN VIBRATING APPARATUS June 20, 1950 2 Sheets-Sheet 2 Filed Oct. 3, 1944 l Illll Invenlr @607:76 E Sl'rap Patented June 20, 1950 VIBRATING APPARATUS George Harry Strain, Seafood, England Application October 3, 1944, Serial No. 557,001 In Great Britain December 1, 1943 3 Claims.

The present. invention relates to vibrating apparatus for screening, dehydrating or agitating material, the apparatus being of the kind in which the vibratory movements of a primary mass, preferably in the form of an anvil, are imparted to a secondary mass, which carries the material to be treated, by means of an elastic coupling. Machines of this type are marketed under the trade-mark Velosifter registered in the name of the present applicant.

When these machines are in use the two masses are caused alternately to collide and separate, resulting in an unusual motion of the secondary mass.

According to the present invention means are provided whereby collision between the primary and secondary masses can be caused to occur at either endof a stroke or at both ends of a stroke, at the will of the operator, the motion of the secondary mass being suddenly arrested and reversed. The secondary mass, which is in the form of screening compartments or liquid containers, is clamped to a bridge or platform supported between springs which determine the natural frequency of the secondary mass so that it keeps in step with primary mass.

If collision occurs at the the upper end of a stroke, material resting on a screen, and tending to lodge in the apertures, is projected upwardly, and thel apertures are cleared for the passage of particles when they return to the screen under the action of gravity.

When powdered or broken material is wet and has to be de-watered, the apertures of the screen should be small enough to prevent the passage of material and large enough to allow the liquid to pass through. When the apertures are small, water has a strong tendency to reside in them in the form of globules or films. If collision occurs at the upper end of the stroke, water may be ejected from the apertures in an upward direction together with the material, but on returning to the screen the globules are reformed and the liquid tends to cling to the screen instead of passing through.

If collision occurs at the lower end of the stroke, water is ejected from the apertures, with the assistance of gravity, in a downward direction and it leaves the underside of the screen in the form of spray while the material is retained above the screen. While this is happening certain materials have a tendency to lodge in the apertures and cannot be removed without an ejecting action in an upward direction. If collision is made to occur at both ends of the stroke,

the upper collision frees the apertures of lodging material and the lower collision removes the water.

The screening vibrations are rectilinear in character, and if the screens are mounted as shown, the vibrations are perpendicular to the screening surfaces. The screening compartments shown consist of separate sections placed one above the other and clamped firmly together to form chambers enclosed by a lid and bottom for collecting the finest grade of material. A batch of unscreened material is placed in the upper compartment to be segregated according to the underlying screens which may be of any number, the products being removed when the compartments are separated from the machine. This constitutes the batch method of screening. For continuous screening, the compartments would be open at the ends and the surfaces could be inclined by tilting the machine as a whole, or by inclining the screens relatively to the machine, so that material would proceed continuously over the surfaces with the assistance of gravity.

One form of construction of the invention as applied to a vertically operating screening device, is illustrated in the annexed drawings, in which:

Fig. 1 is a side elevation, and

Fig. 2 is a section on the line 2 2 of Fig. l.

In these drawings, the anvil or primary mass I is held and supported by parallel leaf springs 2 secured to a part of the stationary framework 3. The springs 2 guide the anvil so that its motion is substantially rectilinear; they also provide the anvil with a natural frequency which corresponds with the frequency of an unbalanced weight 4 made to rotate about an axle 5 which is secured to the anvil and driven by a belt 6 from a convenient source.

By this arrangement, very little force is needed to vibrate the anvil in the region of its natural frequency and the magnitude of the force is too small to disturb the stationary framework to a noticeable extent.

The secondary mass, comprising screening compartments or containers for liquid or other material, is mounted above the anvil, and guide rods 1 passing freely through holes in the anvil maintain the desired position of the secondary mass relatively to the anvil. The rods 'l are also extended upwards to terminate in screws and wing nuts 8 for clamping the compartments or containers to a, bridge piece 9 which is secured to the middle part of the rods. The lower ends of the rods 1 are screwed and provided with rubber annular discs or pads l secured to adjustable supports H which are held in the desired position by locknuts 52. The bridge or platform 9 is supported between pairs ol' coil springs I3. These springs determine the natural frequency of the secondary mass so that it keeps in step with the anvil, and each pair of springs is compressed by a screwed rod la passing through the springs and a clearance in either end of the bridge 9. By turning wine-nuts E5 the position of the bridge 9 relatively to the anvil may be adjusted, so that impacts occur where desired in the vibratory cycle.

If collision is to occur at the upper end of the screening stroke, only the rubber pads I9 are adjusted to strike against and separate from the underside of the anvil, alternately, and the intensity of this action mov be varied by adjusting wing-nuts I5.

If collision is to occur at the lower of the screening stroke, stops lf3 are brouaht into action. These steps, provided with rubber pads E?, are screwed into the upper sur.i ce of the anvil and secured in the desired position by locknuts I8. The rubber pads I0 are then low., ed to prevent them from makina contact with the anvil, so that impact only occurs when the underside of bridge 9 strikes aaainst pads li.

If collision is to occur at both ends of the screening stroke, pads l0 and I'i are all adjusted to be operative, so that two impacts occur in each period of vibration.

It should be mentioned that a vihratory screening action with impacts at both ends of the stroke can be maintained even if the springs I3 are removed from the machine. For this condition very critical adjustment of the stops is essential, and if the load, speed or stop positions vary very slightly, the vibratory action gets out of step and control. T.With sprincs 3 in action, both load and speed may ce varied over a wide range without the secondary mass getting out of step with the anvil.

With this machine, screening vibrations 1% in length and 1750 per minute e e easily obtained, and as impact occurs in the recien of maximum velocity, the ejer-.ting action is very intense and able to keep the apertures of the finest gauze open and clear when sere ning metal powders. Vibration in the v framestationm. u. Work is quite unnoticeable and the machine need not be bolted down. The screenrs., ganzes are not tensioned: inst ad th are mounted upon metal frames la which lie .fetween the streerungY sections 2B. The fraires le) are spanned with metal rods cr hars 2l of suitabley stiifness which are spaced to suit the gauze they have to support. The gauze 22 is secured to the iframe and bars by soft soldering, so that with this arrangement, screening surfaces are cheaply made and changed.

I claim:

1. Vibrating apparatus of the kind specified comprising a vibrating primary mass, a vibrating secondary mass, spring means between said masses, impact means between said masses. means for adjusting said spring means to cause said secondary mass to assume a vibration frequency in step with that of said primary mass. said secondary mass being mounted above said primary mass, a bridge to which said spring means is applied, and guide rods passing through the two masses and serving to clamp the secondary mass to said bridge.

2. Vibrating apparatus of the kind specified comprising a vibrating primary mass, a vibrating secondary mass, spring means between said masses, impact means between said masses, means for adjusting said spring means to cause said secondary mass to assume a vibration frequency in step with that of said primary mass, said secondary mass being mounted above said primary mass, a bridce to which the spring means is applied, guide rods passing through the two masses and serving to clamp the secondary mass to said bridge, elastic pads below the primary mass, and abutment means carried by the lower ends of the guide rods for engaging against said elastic pads.

3. Vibrating apparatus of the kind specified comprising a vibrating primary mass, a Vibrating secondary mass, spring means between said masses, means for adjusting said spring means to cause said secondary mass to assume a vibration frequency in step with that of said primary mas guide rods clamped to the secondary mass and passing through the primary mass, and impact means between the masses comprising upper stops secured to the upper portion of the primary mass in position to make contact with the secondary mass at one end of the screening stroke, and lower stops secured to said guide rods and positioned to make contact with the lower surface of the primary mass at the opposite end of the screening stroke.

GEORGE HARRY STRAIN.

REFERENCES CITED The following references are of record in the 0 file of this patent:

UNITED STATES PATENTS 

